Novel dinuclear cyclometalated Platinum(II) complex as orange phosphorescent emitters for single-emitting-layer white polymer light-emitting diodes

Abstract

Novel binuclear platinum complex (FPT)2Pt2(diPic) and mononuclear platinum complex (FPT)Pt(Pic) were designed and synthesized, where FPT is N-(4-(6-(9,9-diethyl-9H-fluoren-2-yl)pyridin-3-yl)phenyl)N-phenylbenzenamine, diPic is 3-(6-(2-carboxypyridin-3-yloxy)hexyloxy)picolinic acid, and Pic is picolinic acid. The photophysical, electrochemical and thermal properties, as well as electroluminescent (EL) properties for both platinum(II) complexes were studied. Compared to (FPT)Pt(Pic), (FPT)2Pt2(diPic) exhibited stronger phosphorescent emission in PL spectra and higher ΦPL, owing to the enhanced spin-orbit interaction of platinum centers. Moreover, the monochromatic devices based on (FPT)2Pt2(diPic) showed better EL properties than (FPT)Pt(Pic). Based on that, the single-emissive-layer WPLEDs using (FPT)2Pt2(diPic) as orange emitter and FIrpic as blue emitter were also obtained. The WPLEDs show best performances with a maximal LE of 1.3 cd/A, and a CIE coordinates of (0.35, 0.37) which is very close to the pure white emission. Work is still underway to improve the device efficiency and color purity of these iridium and platinum complexes co-doped WPLEDs.